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Note 13.0 MicroPower Run-time Perform. No replies
JAWS::KAISER 254 lines 25-MAR-1985 09:20
--------------------------------------------------------------------------------
+---------------+ +-----------------+
| d i g i t a l | | uNOTE # 013 |
+---------------+ +-----------------+
+----------------------------------------------------+-----------------+
| Title: Run-time System Performance Evaluation | Date: 09-Oct-84 |
| Using MicroPower/Pascal V 1.5 | |
+----------------------------------------------------+-----------------+
| Originator: Herbert Maehner | Page 1 of 5 |
+----------------------------------------------------+-----------------+
In real-time programming, the performance of the run-time system and
the compiler together govern the overall power of the application. The
performance of the MicroPower/Pascal compiler has been extensively
discussed by R.Billig/R.Cronk [1].
The performance of the run-time executive of MicroPower/Pascal is
measured in this MicroNote using different LSI-11 CPU-boards and the
KXT11-CA I/O processor. Data was obtained using MicroPower/Pascal
version 1.5.
Test Conditions
---------------
Results obtained through a lab experiment are only as precise as the
test environment and may only be referenced giving the exact test
conditions.
The goal was to measure the elapsed time of a given primitive execution
on the Pascal process level, i.e. how long it takes to call/execute a
kernel primitive from a Pascal program.
Generally, the following procedure was used to obtain the elapsed time,
where in some cases more than one output bit has been used to obtain
the desired pulse-width.
WHILE Condition = TRUE DO
BEGIN
Out_port.bit0 := TRUE;
{ here call/execute given primitive }
Out_port.bit0 := FALSE;
END;
The whole test was done in a loop as long as the condition was true.
Here, Condition is a boolean variable, which is set FALSE by a high
priorty process waiting on a terminal input (READLN).
The Outport.bit0 is bit0 of a parallel device. The parallel device was
either a DRV11 (using LSI 11/23 and LSI 11/73) or the on-board parallel
device (using the FALCON plus SBC 11/21 and KXT11-CA).
Page 2
The bit0 pulse is used as the input to an oscilloscope which has the
capabilities to measure and display time differences and frequencies.
The elapsed time required to execute the various primitives was
obtained. In addition to the primitive requests some math-functions
times were obtained. The results are shown in Table 1 at the of this
MicroNote.
Interrupt-Test Conditions
-------------------------
A Pascal-program with an embedded interrupt service routine needs
DRIVER privileges in a mapped environment. The test program either
connects to a "normal" ISR or to a prio7 ISR. The program executed a
simple loop like:
WHILE TRUE DO
BEGIN
Out_port.Bit1 := TRUE;
Out_port.Bit1 := FALSE;
END;
The Outport is the parallel device of the type mentioned above. This
is used to monitor process execution behavior. Testing the interrupt
response time, we used a square wave generator which triggered an
interrupt on that parallel device. The ISR was coded as
.ENABL GBL ; Enable global symbols
.MCALL MACDF$,PURE$ ; Set-up pure/impure area
.MCALL IMPUR$
.GLOBL INPORT,OUTPRT ; port A,B of PPI
MACDF$ ; MACDF$ must be called before the
PURE$ ; two assembly directives
.DSABL AMA
PPIINT::
BISB #1,@#OUTPRT ; set bit 0 output port -------
MOVB @#INPORT,@#Temp ; dummy read | ISR time
MOVB @#INPORT,@#Temp ; dummy read | measured
BICB #1,@#OUTPRT ; set bit 0 output port -------
RTS PC ; normal ISR return
RTS R4 ; prio 7 ISR return
IMPUR$
TEMP: .WORD 0 ; reserve one word
.END
Depending upon the ISR-type either the RTS PC or the RTS R4 must be
used to exit the ISR. The first MACRO-statement within the ISR
signaled bit0 of the parallel port. The resulting interrupt dispatch
time was defined as the pulse width given by the square wave generator
Page 3
edge and the signaled output port. This includes the hardware ISR
dispatch time as well. The ISR execution time was given by the pulse
width indicated within ISR source above. Again, all pulses were
measured using an oscilloscope. The maximum interrupt rate was
determined by increasing the square frequency (which in turn increases
the outpt square wave of the ISR) until the system lost interrupts.
Using CONNECT SEMAPHORE the interrupt performance was similarly
measured. In this case only a dynamic process was waiting on the
semaphore to be signaled. The results are shown in table 2.
References
1. Rich Billig and Randy Cronk, A System/Architecture Approach to
Microcomputer Benchmarking, DIGITAL Equipment Corporation,
Sept. 1982, EZ-12053-03/82
2. MicroPower/Pascal Newsletter, Volume 1, No. 1, March 1984, p. 23,
DIGITAL Equipment Corporation, Order Number AV-B067A-TK
Page 4
+---------------+-----------+-----------+-----------+------+------+
| | LSI-11/23 | LSI-11/23 | | | |
| Operation | w/o FPU | w/ FPU | LSI-11/73 | SBC | KXT11|
| | u m | u m | u m |11/21+| -CA |
+---------------+-----------+-----------+-----------+------+------+
|Process | | | | | |
| creation | 3.1 5.48 | 3.56 5.93 | 1.84 2.64 | 3.96 | 2.71 |
| deletion | 2.4 4.19 | 2.55 4.35 | 1.14 1.92 | 2.96 | 2.06 |
+---------------+-----------+-----------+-----------+------+------+
|Schedule + | | | | | |
| Context Switch| 0.56 0.97 | 0.82 1.27 | 0.38 0.57 | 0.69 | 0.49 |
+---------------+-----------+-----------+-----------+------+------+
| Ring_buffer | | | | | |
| 1 character | | | | | |
| get | 0.55 0.96 | 0.55 0.99 | 0.27 0.42 | 0.67 | 0.47 |
| put | 0.50 0.93 | 0.51 0.95 | 0.25 0.39 | 0.63 | 0.43 |
| 2 characters | | | | | |
| get | 0.61 1.05 | 0.61 1.05 | 0.29 0.43 | 0.72 | 0.51 |
| put | 0.58 1.01 | 0.58 1.02 | 0.28 0.42 | 0.70 | 0.49 |
| 4 characters | | | | | |
| get | 0.73 1.20 | 0.73 1.18 | 0.36 0.50 | 0.88 | 0.62 |
| put | 0.71 1.17 | 0.71 1.15 | 0.35 0.49 | 0.86 | 0.60 |
| Signal Semaphr| | | | | |
| by descriptor| 0.35 0.64 | 0.35 0.65 | 0.16 0.25 | 0.44 | 0.30 |
| by name | 0.61 0.93 | 0.61 0.94 | 0.27 0.37 | 0.75 | 0.52 |
| fast named | 0.36 0.65 | 0.36 0.66 | 0.17 0.29 | 0.44 | 0.30 |
+---------------+-----------+-----------+-----------+------+------+
| Get_status | 0.42 0.84 | 0.42 0.85 | 0.20 0.33 | 0.50 | 0.35 |
+---------------+-----------+-----------+-----------+------+------+
| Send + Receive| | | | | |
| (by value) | | | | | |
| - 1 Byte | 1.17 2.18 | 1.18 2.20 | 0.59 0.89 | 1.45 | 1.01 |
| - 34 Bytes| 1.46 2.50 | 1.46 2.51 | 0.73 1.11 | 1.79 | 1.24 |
| Send + Receive| | | | | |
| (by reference)| | | | | |
| - 10 Bytes| 1.26 2.28 | 1.26 2.31 | 0.67 0.96 | 1.54 | 1.08 |
| - 100 Bytes| 1.59 2.64 | 1.59 2.67 | 0.84 1.14 | 1.94 | 1.35 |
| - 500 Bytes| 3.09 4.32 | 3.09 4.35 | 1.74 2.11 | 3.78 | 2.63 |
+---------------+-----------+-----------+-----------+------+------+
| TAN | 6.84 7.74 | 1.64 1.68 | 0.35 0.36 | 9.00 | 6.24 |
+---------------+-----------+-----------+-----------+------+------+
| SIN | 5.13 5.82 | 1.75 1.78 | 0.33 0.34 | 6.80 | 4.69 |
+---------------+-----------+-----------+-----------+------+------+
| COS | 6.19 7.00 | 1.94 1.98 | 0.39 0.39 | 8.15 | 5.64 |
+---------------+-----------+-----------+-----------+------+------+
| EXP | 5.04 5.69 | 1.45 1.48 | 0.32 0.33 | 6.55 | 4.59 |
+---------------+-----------+-----------+-----------+------+------+
| LN | 5.34 6.01 | 1.27 1.31 | 0.28 0.29 | 6.95 | 4.86 |
+---------------+-----------+-----------+-----------+------+------+
Table 1: MicroPower/Pascal V1.5 Runtime System (millisec)
Page 5
Notes for Table 1
-----------------
o u = without MMU and m = with MMU
o FPU = with floating point unit (KEF11)
o Send/Receive without context-switch
o SBC-11/21+ using on-board memory only
+------------------------+-----------+-----------+-------+-------+
| Operation | LSI-11/23 | LSI-11/73 | SBC | KXT11 |
| | u m | u m | 11/21+| -CA |
+------------------------+-----------+-----------+-------+-------+
| ISR: | | | | |
| | | | | |
| Interrupt dispatch- | | | | |
| time (usec) | 62 91 | 42 54 | 81 | 61 |
| | | | | |
| ISR execution | | | | |
| time (usec) | 20 23 | 13.4 | 21 | 16 |
| | | | | |
| Maximal interrupt- | | | | |
| frequency (kHz) | 7.0 5.1 | 12.9 10.9 | 4.8 | 7.5 |
+------------------------+-----------+-----------+-------+-------+
| PRIO7 ISR: | | | | |
| | | | | |
| Interrupt dispatch- | | | | |
| time (usec) | 28.5 60 | 22 38 | 32 | 28 |
| | | | | |
| ISR execution | | | | |
| time (usec) | 20 24 | 13.4 | 21 | 16 |
| | | | | |
| Maximal interrupt- | | | | |
| frequency (kHz) | 17.8 9.3 | 26 16 | 12.8 | 16.5 |
+------------------------+-----------+-----------+-------+-------+
| CONNECT_SEMAPHORE: (one process waiting on that semaphore) |
| |
| Interrupt dispatch + | | | | |
| context-switch time | | | | |
| (msec) | 0.88 1.36 | 0.49 0.63 | 1.15 | 0.82 |
| | | | | |
| Maximal interrupt- | | | | |
| frequency (kHz) | 0.67 0.39 | 1.20 0.83 | 0.41 | 0.75 |
+------------------------+-----------+-----------+-------+-------+
Table 2: Interrupt Performance
Note for Table 2
----------------
Additionally, the system had to service the clock interrupt
at a rate of 50 Hz without the clock driver implemented, i.e.
the interrupt dispatcher discarded the interrupt. The clock
interrupt was enabled because realistically most systems have
the clock enabled.
